<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined ( 'BASEPATH' ) or exit ( 'No direct script access allowed' );

/**
 * Loader Class
 *
 * Loads framework components.
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Loader
 * @author		EllisLab Dev Team
 * @link		https://codeigniter.com/user_guide/libraries/loader.html
 */
class CI_Loader {

	// All these are set automatically. Don't mess with them.
	/**
	 * Nesting level of the output buffering mechanism
	 *
	 * @var	int
	 */
	protected $_ci_ob_level;

	/**
	 * List of paths to load views from
	 *
	 * @var	array
	 */
	protected $_ci_view_paths = array (VIEWPATH => TRUE );

	/**
	 * List of paths to load libraries from
	 *
	 * @var	array
	 */
	protected $_ci_library_paths = array (APPPATH, BASEPATH );

	/**
	 * List of paths to load models from
	 *
	 * @var	array
	 */
	protected $_ci_model_paths = array (APPPATH );

	/**
	 * List of paths to load helpers from
	 *
	 * @var	array
	 */
	protected $_ci_helper_paths = array (APPPATH, BASEPATH );

	/**
	 * List of cached variables
	 *
	 * @var	array
	 */
	protected $_ci_cached_vars = array ();

	/**
	 * List of loaded classes
	 *
	 * @var	array
	 */
	protected $_ci_classes = array ();

	/**
	 * List of loaded models
	 *
	 * @var	array
	 */
	protected $_ci_models = array ();

	/**
	 * List of loaded helpers
	 *
	 * @var	array
	 */
	protected $_ci_helpers = array ();

	/**
	 * List of class name mappings
	 *
	 * @var	array
	 */
	protected $_ci_varmap = array ('unit_test' => 'unit', 'user_agent' => 'agent' );

	// --------------------------------------------------------------------


	/**
	 * Class constructor
	 *
	 * Sets component load paths, gets the initial output buffering level.
	 *
	 * @return	void
	 */
	public function __construct() {
		$this->_ci_ob_level = ob_get_level ();
		$this->_ci_classes = & is_loaded ();

		log_message ( 'info', 'Loader Class Initialized' );
	}

	// --------------------------------------------------------------------


	/**
	 * Initializer
	 *
	 * @todo	Figure out a way to move this to the constructor
	 * without breaking *package_path*() methods.
	 * @uses	CI_Loader::_ci_autoloader()
	 * @used-by	CI_Controller::__construct()
	 * @return	void
	 */
	public function initialize() {
		$this->_ci_autoloader ();
	}

	// --------------------------------------------------------------------


	/**
	 * Is Loaded
	 *
	 * A utility method to test if a class is in the self::$_ci_classes array.
	 *
	 * @used-by	Mainly used by Form Helper function _get_validation_object().
	 *
	 * @param 	string		$class	Class name to check for
	 * @return 	string|bool	Class object name if loaded or FALSE
	 */
	public function is_loaded($class) {
		return array_search ( ucfirst ( $class ), $this->_ci_classes, TRUE );
	}

	// --------------------------------------------------------------------


	/**
	 * Library Loader
	 *
	 * Loads and instantiates libraries.
	 * Designed to be called from application controllers.
	 *
	 * @param	mixed	$library	Library name
	 * @param	array	$params		Optional parameters to pass to the library class constructor
	 * @param	string	$object_name	An optional object name to assign to
	 * @return	object
	 */
	public function library($library, $params = NULL, $object_name = NULL) {
		if (empty ( $library )) {
			return $this;
		} elseif (is_array ( $library )) {
			foreach ( $library as $key => $value ) {
				if (is_int ( $key )) {
					$this->library ( $value, $params );
				} else {
					$this->library ( $key, $params, $value );
				}
			}

			return $this;
		}

		if ($params !== NULL && ! is_array ( $params )) {
			$params = NULL;
		}

		$this->_ci_load_library ( $library, $params, $object_name );
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Model Loader
	 *
	 * Loads and instantiates models.
	 *
	 * @param	string	$model		Model name
	 * @param	string	$name		An optional object name to assign to
	 * @param	bool	$db_conn	An optional database connection configuration to initialize
	 * @return	object
	 */
	public function model($model, $name = '', $db_conn = FALSE) {
		if (empty ( $model )) {
			return $this;
		} elseif (is_array ( $model )) {
			foreach ( $model as $key => $value ) {
				is_int ( $key ) ? $this->model ( $value, '', $db_conn ) : $this->model ( $key, $value, $db_conn );
			}

			return $this;
		}

		$path = '';

		// Is the model in a sub-folder? If so, parse out the filename and path.
		if (($last_slash = strrpos ( $model, '/' )) !== FALSE) {
			// The path is in front of the last slash
			$path = substr ( $model, 0, ++ $last_slash );

			// And the model name behind it
			$model = substr ( $model, $last_slash );

		}

		if (empty ( $name )) {
			$name = $model;
		}

		if (in_array ( $name, $this->_ci_models, TRUE )) {
			return $this;
		}

		$CI = & get_instance ();
		if (isset ( $CI->$name )) {
			throw new RuntimeException ( 'The model name you are loading is the name of a resource that is already being used: ' . $name );
		}

		if ($db_conn !== FALSE && ! class_exists ( 'CI_DB', FALSE )) {
			if ($db_conn === TRUE) {
				$db_conn = '';
			}

			$this->database ( $db_conn, FALSE, TRUE );
		}

		// Note: All of the code under this condition used to be just:
		//
		//       load_class('Model', 'core');
		//
		//       However, load_class() instantiates classes
		//       to cache them for later use and that prevents
		//       MY_Model from being an abstract class and is
		//       sub-optimal otherwise anyway.
		if (! class_exists ( 'CI_Model', FALSE )) {
			$app_path = APPPATH . 'core' . DIRECTORY_SEPARATOR;
			if (file_exists ( $app_path . 'Model.php' )) {
				require_once ($app_path . 'Model.php');
				if (! class_exists ( 'CI_Model', FALSE )) {
					throw new RuntimeException ( $app_path . "Model.php exists, but doesn't declare class CI_Model" );
				}
			} elseif (! class_exists ( 'CI_Model', FALSE )) {
				require_once (BASEPATH . 'core' . DIRECTORY_SEPARATOR . 'Model.php');
			}

			$class = config_item ( 'subclass_prefix' ) . 'Model';
			if (file_exists ( $app_path . $class . '.php' )) {
				require_once ($app_path . $class . '.php');
				if (! class_exists ( $class, FALSE )) {
					throw new RuntimeException ( $app_path . $class . ".php exists, but doesn't declare class " . $class );
				}
			}
		}

		$model = ucfirst ( $model );

		if (! class_exists ( $model, FALSE )) {
			foreach ( $this->_ci_model_paths as $mod_path ) {
				if (! file_exists ( $mod_path . 'models/' . $path . $model . '.php' )) {
					continue;
				}

				require_once ($mod_path . 'models/' . $path . $model . '.php');
				if (! class_exists ( $model, FALSE )) {
					throw new RuntimeException ( $mod_path . "models/" . $path . $model . ".php exists, but doesn't declare class " . $model );
				}

				break;
			}

			if (! class_exists ( $model, FALSE )) {
				throw new RuntimeException ( 'Unable to locate the model you have specified: ' . $model );
			}
		} elseif (! is_subclass_of ( $model, 'CI_Model' )) {
			throw new RuntimeException ( "Class " . $model . " already exists and doesn't extend CI_Model" );
		}

		$this->_ci_models [] = $name;
		$CI->$name = new $model ();
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Database Loader
	 *
	 * @param	mixed	$params		Database configuration options
	 * @param	bool	$return 	Whether to return the database object
	 * @param	bool	$query_builder	Whether to enable Query Builder
	 * (overrides the configuration setting)
	 *
	 * @return	object|bool	Database object if $return is set to TRUE,
	 * FALSE on failure, CI_Loader instance in any other case
	 */
	public function database($params = '', $return = FALSE, $query_builder = NULL) {
		// Grab the super object
		$CI = & get_instance ();

		// Do we even need to load the database class?
		if ($return === FALSE && $query_builder === NULL && isset ( $CI->db ) && is_object ( $CI->db ) && ! empty ( $CI->db->conn_id )) {
			return FALSE;
		}

		require_once (BASEPATH . 'database/DB.php');

		if ($return === TRUE) {
			return DB ( $params, $query_builder );
		}

		// Initialize the db variable. Needed to prevent
		// reference errors with some configurations
		$CI->db = '';

		// Load the DB class
		$CI->db = & DB ( $params, $query_builder );
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Load the Database Utilities Class
	 *
	 * @param	object	$db	Database object
	 * @param	bool	$return	Whether to return the DB Utilities class object or not
	 * @return	object
	 */
	public function dbutil($db = NULL, $return = FALSE) {
		$CI = & get_instance ();

		if (! is_object ( $db ) or ! ($db instanceof CI_DB)) {
			class_exists ( 'CI_DB', FALSE ) or $this->database ();
			$db = & $CI->db;
		}

		require_once (BASEPATH . 'database/DB_utility.php');
		require_once (BASEPATH . 'database/drivers/' . $db->dbdriver . '/' . $db->dbdriver . '_utility.php');
		$class = 'CI_DB_' . $db->dbdriver . '_utility';

		if ($return === TRUE) {
			return new $class ( $db );
		}

		$CI->dbutil = new $class ( $db );
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Load the Database Forge Class
	 *
	 * @param	object	$db	Database object
	 * @param	bool	$return	Whether to return the DB Forge class object or not
	 * @return	object
	 */
	public function dbforge($db = NULL, $return = FALSE) {
		$CI = & get_instance ();
		if (! is_object ( $db ) or ! ($db instanceof CI_DB)) {
			class_exists ( 'CI_DB', FALSE ) or $this->database ();
			$db = & $CI->db;
		}

		require_once (BASEPATH . 'database/DB_forge.php');
		require_once (BASEPATH . 'database/drivers/' . $db->dbdriver . '/' . $db->dbdriver . '_forge.php');

		if (! empty ( $db->subdriver )) {
			$driver_path = BASEPATH . 'database/drivers/' . $db->dbdriver . '/subdrivers/' . $db->dbdriver . '_' . $db->subdriver . '_forge.php';
			if (file_exists ( $driver_path )) {
				require_once ($driver_path);
				$class = 'CI_DB_' . $db->dbdriver . '_' . $db->subdriver . '_forge';
			}
		} else {
			$class = 'CI_DB_' . $db->dbdriver . '_forge';
		}

		if ($return === TRUE) {
			return new $class ( $db );
		}

		$CI->dbforge = new $class ( $db );
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * View Loader
	 *
	 * Loads "view" files.
	 *
	 * @param	string	$view	View name
	 * @param	array	$vars	An associative array of data
	 * to be extracted for use in the view
	 * @param	bool	$return	Whether to return the view output
	 * or leave it to the Output class
	 * @return	object|string
	 */
	public function view($view, $vars = array(), $return = FALSE) {
		return $this->_ci_load ( array ('_ci_view' => $view, '_ci_vars' => $this->_ci_prepare_view_vars ( $vars ), '_ci_return' => $return ) );
	}

	// --------------------------------------------------------------------


	/**
	 * Generic File Loader
	 *
	 * @param	string	$path	File path
	 * @param	bool	$return	Whether to return the file output
	 * @return	object|string
	 */
	public function file($path, $return = FALSE) {
		return $this->_ci_load ( array ('_ci_path' => $path, '_ci_return' => $return ) );
	}

	// --------------------------------------------------------------------


	/**
	 * Set Variables
	 *
	 * Once variables are set they become available within
	 * the controller class and its "view" files.
	 *
	 * @param	array|object|string	$vars
	 * An associative array or object containing values
	 * to be set, or a value's name if string
	 * @param 	string	$val	Value to set, only used if $vars is a string
	 * @return	object
	 */
	public function vars($vars, $val = '') {
		$vars = is_string ( $vars ) ? array ($vars => $val ) : $this->_ci_prepare_view_vars ( $vars );

		foreach ( $vars as $key => $val ) {
			$this->_ci_cached_vars [$key] = $val;
		}

		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Clear Cached Variables
	 *
	 * Clears the cached variables.
	 *
	 * @return	CI_Loader
	 */
	public function clear_vars() {
		$this->_ci_cached_vars = array ();
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Get Variable
	 *
	 * Check if a variable is set and retrieve it.
	 *
	 * @param	string	$key	Variable name
	 * @return	mixed	The variable or NULL if not found
	 */
	public function get_var($key) {
		return isset ( $this->_ci_cached_vars [$key] ) ? $this->_ci_cached_vars [$key] : NULL;
	}

	// --------------------------------------------------------------------


	/**
	 * Get Variables
	 *
	 * Retrieves all loaded variables.
	 *
	 * @return	array
	 */
	public function get_vars() {
		return $this->_ci_cached_vars;
	}

	// --------------------------------------------------------------------


	/**
	 * Helper Loader
	 *
	 * @param	string|string[]	$helpers	Helper name(s)
	 * @return	object
	 */
	public function helper($helpers = array()) {
		is_array ( $helpers ) or $helpers = array ($helpers );
		foreach ( $helpers as &$helper ) {
			$filename = basename ( $helper );
			$filepath = ($filename === $helper) ? '' : substr ( $helper, 0, strlen ( $helper ) - strlen ( $filename ) );
			$filename = strtolower ( preg_replace ( '#(_helper)?(\.php)?$#i', '', $filename ) ) . '_helper';
			$helper = $filepath . $filename;

			if (isset ( $this->_ci_helpers [$helper] )) {
				continue;
			}

			// Is this a helper extension request?
			$ext_helper = config_item ( 'subclass_prefix' ) . $filename;
			$ext_loaded = FALSE;
			foreach ( $this->_ci_helper_paths as $path ) {
				if (file_exists ( $path . 'helpers/' . $ext_helper . '.php' )) {
					include_once ($path . 'helpers/' . $ext_helper . '.php');
					$ext_loaded = TRUE;
				}
			}

			// If we have loaded extensions - check if the base one is here
			if ($ext_loaded === TRUE) {
				$base_helper = BASEPATH . 'helpers/' . $helper . '.php';
				if (! file_exists ( $base_helper )) {
					show_error ( 'Unable to load the requested file: helpers/' . $helper . '.php' );
				}

				include_once ($base_helper);
				$this->_ci_helpers [$helper] = TRUE;
				log_message ( 'info', 'Helper loaded: ' . $helper );
				continue;
			}

			// No extensions found ... try loading regular helpers and/or overrides
			foreach ( $this->_ci_helper_paths as $path ) {
				if (file_exists ( $path . 'helpers/' . $helper . '.php' )) {
					include_once ($path . 'helpers/' . $helper . '.php');

					$this->_ci_helpers [$helper] = TRUE;
					log_message ( 'info', 'Helper loaded: ' . $helper );
					break;
				}
			}

			// unable to load the helper
			if (! isset ( $this->_ci_helpers [$helper] )) {
				show_error ( 'Unable to load the requested file: helpers/' . $helper . '.php' );
			}
		}

		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Load Helpers
	 *
	 * An alias for the helper() method in case the developer has
	 * written the plural form of it.
	 *
	 * @uses	CI_Loader::helper()
	 * @param	string|string[]	$helpers	Helper name(s)
	 * @return	object
	 */
	public function helpers($helpers = array()) {
		return $this->helper ( $helpers );
	}

	// --------------------------------------------------------------------


	/**
	 * Language Loader
	 *
	 * Loads language files.
	 *
	 * @param	string|string[]	$files	List of language file names to load
	 * @param	string		Language name
	 * @return	object
	 */
	public function language($files, $lang = '') {
		get_instance ()->lang->load ( $files, $lang );
		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Config Loader
	 *
	 * Loads a config file (an alias for CI_Config::load()).
	 *
	 * @uses	CI_Config::load()
	 * @param	string	$file			Configuration file name
	 * @param	bool	$use_sections		Whether configuration values should be loaded into their own section
	 * @param	bool	$fail_gracefully	Whether to just return FALSE or display an error message
	 * @return	bool	TRUE if the file was loaded correctly or FALSE on failure
	 */
	public function config($file, $use_sections = FALSE, $fail_gracefully = FALSE) {
		return get_instance ()->config->load ( $file, $use_sections, $fail_gracefully );
	}

	// --------------------------------------------------------------------


	/**
	 * Driver Loader
	 *
	 * Loads a driver library.
	 *
	 * @param	string|string[]	$library	Driver name(s)
	 * @param	array		$params		Optional parameters to pass to the driver
	 * @param	string		$object_name	An optional object name to assign to
	 *
	 * @return	object|bool	Object or FALSE on failure if $library is a string
	 * and $object_name is set. CI_Loader instance otherwise.
	 */
	public function driver($library, $params = NULL, $object_name = NULL) {
		if (is_array ( $library )) {
			foreach ( $library as $key => $value ) {
				if (is_int ( $key )) {
					$this->driver ( $value, $params );
				} else {
					$this->driver ( $key, $params, $value );
				}
			}

			return $this;
		} elseif (empty ( $library )) {
			return FALSE;
		}

		if (! class_exists ( 'CI_Driver_Library', FALSE )) {
			// We aren't instantiating an object here, just making the base class available
			require BASEPATH . 'libraries/Driver.php';
		}

		// We can save the loader some time since Drivers will *always* be in a subfolder,
		// and typically identically named to the library
		if (! strpos ( $library, '/' )) {
			$library = ucfirst ( $library ) . '/' . $library;
		}

		return $this->library ( $library, $params, $object_name );
	}

	// --------------------------------------------------------------------


	/**
	 * Add Package Path
	 *
	 * Prepends a parent path to the library, model, helper and config
	 * path arrays.
	 *
	 * @see	CI_Loader::$_ci_library_paths
	 * @see	CI_Loader::$_ci_model_paths
	 * @see CI_Loader::$_ci_helper_paths
	 * @see CI_Config::$_config_paths
	 *
	 * @param	string	$path		Path to add
	 * @param 	bool	$view_cascade	(default: TRUE)
	 * @return	object
	 */
	public function add_package_path($path, $view_cascade = TRUE) {
		$path = rtrim ( $path, '/' ) . '/';

		array_unshift ( $this->_ci_library_paths, $path );
		array_unshift ( $this->_ci_model_paths, $path );
		array_unshift ( $this->_ci_helper_paths, $path );

		$this->_ci_view_paths = array ($path . 'views/' => $view_cascade ) + $this->_ci_view_paths;

		// Add config file path
		$config = & $this->_ci_get_component ( 'config' );
		$config->_config_paths [] = $path;

		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Get Package Paths
	 *
	 * Return a list of all package paths.
	 *
	 * @param	bool	$include_base	Whether to include BASEPATH (default: FALSE)
	 * @return	array
	 */
	public function get_package_paths($include_base = FALSE) {
		return ($include_base === TRUE) ? $this->_ci_library_paths : $this->_ci_model_paths;
	}

	// --------------------------------------------------------------------


	/**
	 * Remove Package Path
	 *
	 * Remove a path from the library, model, helper and/or config
	 * path arrays if it exists. If no path is provided, the most recently
	 * added path will be removed removed.
	 *
	 * @param	string	$path	Path to remove
	 * @return	object
	 */
	public function remove_package_path($path = '') {
		$config = & $this->_ci_get_component ( 'config' );

		if ($path === '') {
			array_shift ( $this->_ci_library_paths );
			array_shift ( $this->_ci_model_paths );
			array_shift ( $this->_ci_helper_paths );
			array_shift ( $this->_ci_view_paths );
			array_pop ( $config->_config_paths );
		} else {
			$path = rtrim ( $path, '/' ) . '/';
			foreach ( array ('_ci_library_paths', '_ci_model_paths', '_ci_helper_paths' ) as $var ) {
				if (($key = array_search ( $path, $this->{$var} )) !== FALSE) {
					unset ( $this->{$var} [$key] );
				}
			}

			if (isset ( $this->_ci_view_paths [$path . 'views/'] )) {
				unset ( $this->_ci_view_paths [$path . 'views/'] );
			}

			if (($key = array_search ( $path, $config->_config_paths )) !== FALSE) {
				unset ( $config->_config_paths [$key] );
			}
		}

		// make sure the application default paths are still in the array
		$this->_ci_library_paths = array_unique ( array_merge ( $this->_ci_library_paths, array (APPPATH, BASEPATH ) ) );
		$this->_ci_helper_paths = array_unique ( array_merge ( $this->_ci_helper_paths, array (APPPATH, BASEPATH ) ) );
		$this->_ci_model_paths = array_unique ( array_merge ( $this->_ci_model_paths, array (APPPATH ) ) );
		$this->_ci_view_paths = array_merge ( $this->_ci_view_paths, array (APPPATH . 'views/' => TRUE ) );
		$config->_config_paths = array_unique ( array_merge ( $config->_config_paths, array (APPPATH ) ) );

		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Internal CI Data Loader
	 *
	 * Used to load views and files.
	 *
	 * Variables are prefixed with _ci_ to avoid symbol collision with
	 * variables made available to view files.
	 *
	 * @used-by	CI_Loader::view()
	 * @used-by	CI_Loader::file()
	 * @param	array	$_ci_data	Data to load
	 * @return	object
	 */
	protected function _ci_load($_ci_data) {
		// Set the default data variables
		foreach ( array ('_ci_view', '_ci_vars', '_ci_path', '_ci_return' ) as $_ci_val ) {
			$$_ci_val = isset ( $_ci_data [$_ci_val] ) ? $_ci_data [$_ci_val] : FALSE;
		}

		$file_exists = FALSE;

		// Set the path to the requested file
		if (is_string ( $_ci_path ) && $_ci_path !== '') {
			$_ci_x = explode ( '/', $_ci_path );
			$_ci_file = end ( $_ci_x );
		} else {
			$_ci_ext = pathinfo ( $_ci_view, PATHINFO_EXTENSION );
			$_ci_file = ($_ci_ext === '') ? $_ci_view . TMP_PREX : $_ci_view;
			foreach ( $this->_ci_view_paths as $_ci_view_file => $cascade ) {
				if (file_exists ( $_ci_view_file . $_ci_file )) {
					$_ci_path = $_ci_view_file . $_ci_file;
					$file_exists = TRUE;
					break;
				}

				if (! $cascade) {
					break;
				}
			}
		}

		if (! $file_exists && ! file_exists ( $_ci_path )) {
			show_error ( 'Unable to load the requested file: ' . $_ci_file );
		}

		// This allows anything loaded using $this->load (views, files, etc.)
		// to become accessible from within the Controller and Model functions.
		$_ci_CI = & get_instance ();
		foreach ( get_object_vars ( $_ci_CI ) as $_ci_key => $_ci_var ) {
			if (! isset ( $this->$_ci_key )) {
				$this->$_ci_key = & $_ci_CI->$_ci_key;
			}
		}

		/*
		 * Extract and cache variables
		 *
		 * You can either set variables using the dedicated $this->load->vars()
		 * function or via the second parameter of this function. We'll merge
		 * the two types and cache them so that views that are embedded within
		 * other views can have access to these variables.
		 */
		empty ( $_ci_vars ) or $this->_ci_cached_vars = array_merge ( $this->_ci_cached_vars, $_ci_vars );
		extract ( $this->_ci_cached_vars );

		/*
		 * Buffer the output
		 *
		 * We buffer the output for two reasons:
		 * 1. Speed. You get a significant speed boost.
		 * 2. So that the final rendered template can be post-processed by
		 *	the output class. Why do we need post processing? For one thing,
		 *	in order to show the elapsed page load time. Unless we can
		 *	intercept the content right before it's sent to the browser and
		 *	then stop the timer it won't be accurate.
		 */
		ob_start ();

		// If the PHP installation does not support short tags we'll
		// do a little string replacement, changing the short tags
		// to standard PHP echo statements.
		if (! is_php ( '5.4' ) && ! ini_get ( 'short_open_tag' ) && config_item ( 'rewrite_short_tags' ) === TRUE) {
			echo eval ( '?>' . preg_replace ( '/;*\s*\?>/', '; ?>', str_replace ( '<?=', '<?php echo ', file_get_contents ( $_ci_path ) ) ) );
		} else {
			include ($_ci_path); // include() vs include_once() allows for multiple views with the same name
		}

		log_message ( 'info', 'File loaded: ' . $_ci_path );

		// Return the file data if requested
		if ($_ci_return === TRUE) {
			$buffer = ob_get_contents ();
			@ob_end_clean ();
			return $buffer;
		}

		/*
		 * Flush the buffer... or buff the flusher?
		 *
		 * In order to permit views to be nested within
		 * other views, we need to flush the content back out whenever
		 * we are beyond the first level of output buffering so that
		 * it can be seen and included properly by the first included
		 * template and any subsequent ones. Oy!
		 */
		if (ob_get_level () > $this->_ci_ob_level + 1) {
			ob_end_flush ();
		} else {
			$_ci_CI->output->append_output ( ob_get_contents () );
			@ob_end_clean ();
		}

		return $this;
	}

	// --------------------------------------------------------------------


	/**
	 * Internal CI Library Loader
	 *
	 * @used-by	CI_Loader::library()
	 * @uses	CI_Loader::_ci_init_library()
	 *
	 * @param	string	$class		Class name to load
	 * @param	mixed	$params		Optional parameters to pass to the class constructor
	 * @param	string	$object_name	Optional object name to assign to
	 * @return	void
	 */
	protected function _ci_load_library($class, $params = NULL, $object_name = NULL) {
		// Get the class name, and while we're at it trim any slashes.
		// The directory path can be included as part of the class name,
		// but we don't want a leading slash
		$class = str_replace ( '.php', '', trim ( $class, '/' ) );

		// Was the path included with the class name?
		// We look for a slash to determine this
		if (($last_slash = strrpos ( $class, '/' )) !== FALSE) {
			// Extract the path
			$subdir = substr ( $class, 0, ++ $last_slash );

			// Get the filename from the path
			$class = substr ( $class, $last_slash );
		} else {
			$subdir = '';
		}

		$class = ucfirst ( $class );

		// Is this a stock library? There are a few special conditions if so ...
		if (file_exists ( BASEPATH . 'libraries/' . $subdir . $class . '.php' )) {
			return $this->_ci_load_stock_library ( $class, $subdir, $params, $object_name );
		}

		// Safety: Was the class already loaded by a previous call?
		if (class_exists ( $class, FALSE )) {
			$property = $object_name;
			if (empty ( $property )) {
				$property = strtolower ( $class );
				isset ( $this->_ci_varmap [$property] ) && $property = $this->_ci_varmap [$property];
			}

			$CI = & get_instance ();
			if (isset ( $CI->$property )) {
				log_message ( 'debug', $class . ' class already loaded. Second attempt ignored.' );
				return;
			}

			return $this->_ci_init_library ( $class, '', $params, $object_name );
		}

		// Let's search for the requested library file and load it.
		foreach ( $this->_ci_library_paths as $path ) {
			// BASEPATH has already been checked for
			if ($path === BASEPATH) {
				continue;
			}

			$filepath = $path . 'libraries/' . $subdir . $class . '.php';
			// Does the file exist? No? Bummer...
			if (! file_exists ( $filepath )) {
				continue;
			}

			include_once ($filepath);
			return $this->_ci_init_library ( $class, '', $params, $object_name );
		}

		// One last attempt. Maybe the library is in a subdirectory, but it wasn't specified?
		if ($subdir === '') {
			return $this->_ci_load_library ( $class . '/' . $class, $params, $object_name );
		}

		// If we got this far we were unable to find the requested class.
		log_message ( 'error', 'Unable to load the requested class: ' . $class );
		show_error ( 'Unable to load the requested class: ' . $class );
	}

	// --------------------------------------------------------------------


	/**
	 * Internal CI Stock Library Loader
	 *
	 * @used-by	CI_Loader::_ci_load_library()
	 * @uses	CI_Loader::_ci_init_library()
	 *
	 * @param	string	$library_name	Library name to load
	 * @param	string	$file_path	Path to the library filename, relative to libraries/
	 * @param	mixed	$params		Optional parameters to pass to the class constructor
	 * @param	string	$object_name	Optional object name to assign to
	 * @return	void
	 */
	protected function _ci_load_stock_library($library_name, $file_path, $params, $object_name) {
		$prefix = 'CI_';

		if (class_exists ( $prefix . $library_name, FALSE )) {
			if (class_exists ( config_item ( 'subclass_prefix' ) . $library_name, FALSE )) {
				$prefix = config_item ( 'subclass_prefix' );
			}

			$property = $object_name;
			if (empty ( $property )) {
				$property = strtolower ( $library_name );
				isset ( $this->_ci_varmap [$property] ) && $property = $this->_ci_varmap [$property];
			}

			$CI = & get_instance ();
			if (! isset ( $CI->$property )) {
				return $this->_ci_init_library ( $library_name, $prefix, $params, $object_name );
			}

			log_message ( 'debug', $library_name . ' class already loaded. Second attempt ignored.' );
			return;
		}

		$paths = $this->_ci_library_paths;
		array_pop ( $paths ); // BASEPATH
		array_pop ( $paths ); // APPPATH (needs to be the first path checked)
		array_unshift ( $paths, APPPATH );

		foreach ( $paths as $path ) {
			if (file_exists ( $path = $path . 'libraries/' . $file_path . $library_name . '.php' )) {
				// Override
				include_once ($path);
				if (class_exists ( $prefix . $library_name, FALSE )) {
					return $this->_ci_init_library ( $library_name, $prefix, $params, $object_name );
				}

				log_message ( 'debug', $path . ' exists, but does not declare ' . $prefix . $library_name );
			}
		}

		include_once (BASEPATH . 'libraries/' . $file_path . $library_name . '.php');

		// Check for extensions
		$subclass = config_item ( 'subclass_prefix' ) . $library_name;
		foreach ( $paths as $path ) {
			if (file_exists ( $path = $path . 'libraries/' . $file_path . $subclass . '.php' )) {
				include_once ($path);
				if (class_exists ( $subclass, FALSE )) {
					$prefix = config_item ( 'subclass_prefix' );
					break;
				}

				log_message ( 'debug', $path . ' exists, but does not declare ' . $subclass );
			}
		}

		return $this->_ci_init_library ( $library_name, $prefix, $params, $object_name );
	}

	// --------------------------------------------------------------------


	/**
	 * Internal CI Library Instantiator
	 *
	 * @used-by	CI_Loader::_ci_load_stock_library()
	 * @used-by	CI_Loader::_ci_load_library()
	 *
	 * @param	string		$class		Class name
	 * @param	string		$prefix		Class name prefix
	 * @param	array|null|bool	$config		Optional configuration to pass to the class constructor:
	 * FALSE to skip;
	 * NULL to search in config paths;
	 * array containing configuration data
	 * @param	string		$object_name	Optional object name to assign to
	 * @return	void
	 */
	protected function _ci_init_library($class, $prefix, $config = FALSE, $object_name = NULL) {
		// Is there an associated config file for this class? Note: these should always be lowercase
		if ($config === NULL) {
			// Fetch the config paths containing any package paths
			$config_component = $this->_ci_get_component ( 'config' );

			if (is_array ( $config_component->_config_paths )) {
				$found = FALSE;
				foreach ( $config_component->_config_paths as $path ) {
					// We test for both uppercase and lowercase, for servers that
					// are case-sensitive with regard to file names. Load global first,
					// override with environment next
					if (file_exists ( $path . 'config/' . strtolower ( $class ) . '.php' )) {
						include ($path . 'config/' . strtolower ( $class ) . '.php');
						$found = TRUE;
					} elseif (file_exists ( $path . 'config/' . ucfirst ( strtolower ( $class ) ) . '.php' )) {
						include ($path . 'config/' . ucfirst ( strtolower ( $class ) ) . '.php');
						$found = TRUE;
					}

					if (file_exists ( $path . 'config/' . ENVIRONMENT . '/' . strtolower ( $class ) . '.php' )) {
						include ($path . 'config/' . ENVIRONMENT . '/' . strtolower ( $class ) . '.php');
						$found = TRUE;
					} elseif (file_exists ( $path . 'config/' . ENVIRONMENT . '/' . ucfirst ( strtolower ( $class ) ) . '.php' )) {
						include ($path . 'config/' . ENVIRONMENT . '/' . ucfirst ( strtolower ( $class ) ) . '.php');
						$found = TRUE;
					}

					// Break on the first found configuration, thus package
					// files are not overridden by default paths
					if ($found === TRUE) {
						break;
					}
				}
			}
		}

		$class_name = $prefix . $class;

		// Is the class name valid?
		if (! class_exists ( $class_name, FALSE )) {
			log_message ( 'error', 'Non-existent class: ' . $class_name );
			show_error ( 'Non-existent class: ' . $class_name );
		}

		// Set the variable name we will assign the class to
		// Was a custom class name supplied? If so we'll use it
		if (empty ( $object_name )) {
			$object_name = strtolower ( $class );
			if (isset ( $this->_ci_varmap [$object_name] )) {
				$object_name = $this->_ci_varmap [$object_name];
			}
		}

		// Don't overwrite existing properties
		$CI = & get_instance ();
		if (isset ( $CI->$object_name )) {
			if ($CI->$object_name instanceof $class_name) {
				log_message ( 'debug', $class_name . " has already been instantiated as '" . $object_name . "'. Second attempt aborted." );
				return;
			}

			show_error ( "Resource '" . $object_name . "' already exists and is not a " . $class_name . " instance." );
		}

		// Save the class name and object name
		$this->_ci_classes [$object_name] = $class;

		// Instantiate the class
		$CI->$object_name = isset ( $config ) ? new $class_name ( $config ) : new $class_name ();
	}

	// --------------------------------------------------------------------


	/**
	 * CI Autoloader
	 *
	 * Loads component listed in the config/autoload.php file.
	 *
	 * @used-by	CI_Loader::initialize()
	 * @return	void
	 */
	protected function _ci_autoloader() {
		if (file_exists ( APPPATH . 'config/autoload.php' )) {
			include (APPPATH . 'config/autoload.php');
		}

		if (file_exists ( APPPATH . 'config/' . ENVIRONMENT . '/autoload.php' )) {
			include (APPPATH . 'config/' . ENVIRONMENT . '/autoload.php');
		}

		if (! isset ( $autoload )) {
			return;
		}

		// Autoload packages
		if (isset ( $autoload ['packages'] )) {
			foreach ( $autoload ['packages'] as $package_path ) {
				$this->add_package_path ( $package_path );
			}
		}

		// Load any custom config file
		if (count ( $autoload ['config'] ) > 0) {
			foreach ( $autoload ['config'] as $val ) {
				$this->config ( $val );
			}
		}

		// Autoload helpers and languages
		foreach ( array ('helper', 'language' ) as $type ) {
			if (isset ( $autoload [$type] ) && count ( $autoload [$type] ) > 0) {
				$this->$type ( $autoload [$type] );
			}
		}

		// Autoload drivers
		if (isset ( $autoload ['drivers'] )) {
			$this->driver ( $autoload ['drivers'] );
		}

		// Load libraries
		if (isset ( $autoload ['libraries'] ) && count ( $autoload ['libraries'] ) > 0) {
			// Load the database driver.
			if (in_array ( 'database', $autoload ['libraries'] )) {
				$this->database ();
				$autoload ['libraries'] = array_diff ( $autoload ['libraries'], array ('database' ) );
			}

			// Load all other libraries
			$this->library ( $autoload ['libraries'] );
		}

		// Autoload models
		if (isset ( $autoload ['model'] )) {
			$this->model ( $autoload ['model'] );
		}
	}

	// --------------------------------------------------------------------


	/**
	 * Prepare variables for _ci_vars, to be later extract()-ed inside views
	 *
	 * Converts objects to associative arrays and filters-out internal
	 * variable names (i.e. keys prefixed with '_ci_').
	 *
	 * @param	mixed	$vars
	 * @return	array
	 */
	protected function _ci_prepare_view_vars($vars) {
		if (! is_array ( $vars )) {
			$vars = is_object ( $vars ) ? get_object_vars ( $vars ) : array ();
		}

		foreach ( array_keys ( $vars ) as $key ) {
			if (strncmp ( $key, '_ci_', 4 ) === 0) {
				unset ( $vars [$key] );
			}
		}

		return $vars;
	}

	// --------------------------------------------------------------------


	/**
	 * CI Component getter
	 *
	 * Get a reference to a specific library or model.
	 *
	 * @param 	string	$component	Component name
	 * @return	bool
	 */
	protected function &_ci_get_component($component) {
		$CI = & get_instance ();
		return $CI->$component;
	}
}
